Sharif Digital Repository

Currently, in the Islamic Republic of Iran, after aviation accidents and incidents, conversations between pilots and air traffic controllers are re-examined by the State Air Transport Organization of the Islamic Republic of Iran and turned into text. The Automatic Recognition System for Pilot-Air Traffic Service Units’ Communication helps in the implementation of speech recognition. Reducing the time and cost of converting conversations into texts and creating an aviation database in the country are other uses of this system. In this research, after collecting and refining the actual conversation between pilots and air traffic controllers and examining seven methods, we design a system that... 

In this study, the solution of compressible flows is performed using finite volume lattice Boltzmann method (FVLBM). A model associated with 13 discrete velocity vectors and 2 energy levels is used and the Boltzmann transport equation is solved using a cell-centered finite volume on structured meshes. The values of distribution functions on each cell faceare determined by averaging from their values at the two control points located on the center of two neighboring cells. The fourth-order Runge-Kutta time-stepping scheme is applied to discretize temporal derivative term. The second- and fourth-order numerical dissipation termsareadded to the algorithm to stabilize the solution when solving... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have... 

This research aims to study fundamentals of design as a science for possible use in special structures. Special structures are referred to those structures that designers’ knowledge for which are insufficient. Designs of such structures are complex in the sense that we lack all necessary elements of design matrix; as well as proper steps to reach the unknowns. Introducing appropriate design strategy for such structures; we show how a design could be developed without specific needs for trial and errors. In this work, various design methodologies and especially “Axiomatic Design” have been examined. In addition, functional requirement and associated design parameters for structural design are... 

Dynamic analysis of deploying elastic arms of spacecrafts carrying tip mass has been presented. The research concentrates on the precise analytical simulation to reveal the phenomena which are usually eliminated in estimations. One of the most important factors which affect the dynamic response of such arms is rigid body dynamics of spacecraft. Considering this aspect of the problem the evolutionary analytical simulation has been developed through three steps. The first step focuses on the minute simulation of the arm deployment, in which a new mathematical approach called "elastic profile" has been developed which leads to semi-analytical solutions for the arm carrying tip mass.... 

Compressors are one of the most important components of gas turbines and turbomachinery processes. Thus some precise and quick tools are needed for design and analysis purposes. Despite of vast development of Computational Fluid Dynamics (CFD) tools, Through-Flow Streamline Curvature Methods (SCM) has retained their position. 2D and quasi-3D forms of SCM in combination with CFD results nowadays make more than 80% of turbomachinery design process of axial and radial compressors and turbines. In this thesis, the basics of developing a tool for axial-flow compressor analysis are introduced. As will be seen, this analysis tool can be used for design purposes too. The method that is chosen for... 

Axial compression systems are widely used in many aerodynamic applications. However, the operability of such systems is limited at low mass flow rates by fluid dynamic instabilities. These instabilities lead the compressor to rotating stall or surge. In some instances, a combination of rotating stall and surge, called modified surge, has also been observed. In this research Moore – Greitzer model that the principle of constant speed mode checks as a base case has been considered and the developed condition of this model in which the dynamic model of the shaft will also respect and shaft rotational speed as a basis for state shall consider, has been analyzed.
In this study the effect of... 

Pilot-Induced Oscillations is an unwanted, inadvertent phenomenon which has the ability to damage the aircraft completely. This thesis suggests a novel control method that can damp PIO after predicting its occurrence. The specific point of this control algorithm is that it contains a preprocessor that will not let the controller become activated unless in the case of probable PIOs, so pilot forces will not be disturbed in normal flight situations. Besides, with regard to the tendency of pilot towards establishing PIO, this control algorithm decides on pilot and controller shares in the loop. This research focuses on those groups of phenomena which take place as a result of a sudden... 

The objective of this research is to model the wing structure of a flapping wing MAV and investigate structural dynamic behavior of its wing. in this research, to investigate and identify dynamic instabilities, modeling of the structure based on a nonlinear four-node plane element and aerodynamic modeling based on the strip theory in unsteady flow has been done, and by coupling these two models, the final model is formed. In the model of the wing structure, the displacement and changes angle inside the plane of the wing sections have been ignored and only outside the plane have been assumed for the degrees of freedom. In addition, the veins in the flapping wing have been omitted and the... 

Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

The case of rapid small satellite aerial launch by mother airplane has various applications; such as space experiment, weather monitoring, and getting information from the earth monitoring during natural disasters. In this method, the satellite and the launch vehicle will be carried up by mother airplane to the definite height; then, the launch vehicle will be released and flied - to the insert of satellite into the desired orbit. Aerial launch system success depends on a set of complex elements and their interactions. In the present study, first of all, the element interactions will be investigated by system engineering approach based on operational scenarios; then, a new approach for... 

Various factors, such as increasing or decreasing the heat removal from the initial circuit, or increasing the flow rate of the cooling fluid in the reactor, causes the phenomenon of the coolant mixing in the PWR reactors. In this project, the thermohydraulic test of coolant mixing has been simulated in the pressure vessel of the Bushehr nuclear reactor. In this test, the mixing of the coolant caused by the reduction of heat removal from the primary circuit by the secondary circuit is investigated. In this case, the primary circuit temperature increases in the loop where the heat removal is reduced. The most important consequence of this event is the reactivity changes at the core of the... 

This study explores the trajectory optimization of two aircrafts’ formation flight seeking minimization of fuel consumption and flight duration while considering activation of the Traffic Collision Avoidance System (TCAS) during the flights. In order to model the effects of this system, a set of codes has been developed in the Matlab software environment, which utilizes an estimation model of induced drag for each aircraft by their relative positions. Also, position rotation is allowed, and the number and location of rotations are controllable by the user. The TCAS determines the allowable distances between aircrafts during flights based on relative velocities and relative heading angles.... 

In order to ensure the safety of the plants, a set of commissioning tests based on international standards for nuclear power plants is carried out before operation. In this research, one of the Bushehr power plant commissioning tests, the loop connection primary circuit cooling pump test, was simulated using the RELAP5 code. In this test, the effects of loop connection primary circuit pumps on the thermohydraulic parameters and the eneterance of test-related systems was evaluated. After simulating the systems related to the test and extracting the results of the stable state, were evaluated the transient results was obtained with the experimental results of the test of loop connection the... 

This work describes a methodology to enhance aircraft performance via proper mass distribution management. The methodology aims to limit aircraft configuration in early stages of the design process to its desired performance. Mass Distribution Management (MDM), that is used in this work, is a new mathematical model which predicts the so-called aircraft Handling Qualities (HQ) via proper positioning of aircraft mass. This work shows how proper changes in B-747-100 fuel tanks arrangement can enhance its flight quality up to level one during its entire cruise flight without use of any stability augmentation systems. In general this work introduce a methodology to examine different fuel tanks... 

Brain computer interfaces (BCI) are systems designed to understand the brain function from activation patterns and dynamics recorded from the brain activity and use this knowledge to give disabled people the ability to communicate with their surroundings. Features are extracted from recorded signals from the brain while occupied in a mental task and classified into categories related to the task given. These classifiers are then used for the estimation of user anticipation. Usually, the tasks defined are meant to evoke or induce a potential in the pattern of the brain. Awareness of error responses is one of the cognitive functions of the brain which occurs when a response is in conflict with... 

Airline scheduling is a dynamic process in nature such that it changes not only during one year period but also in smaller intervals due to the economic, political, religious, and social factors. Basically, airlines schedule planners through using mathematical models decide which flights are to be served in what periods of time and at what costs. This has to be done considering a set of constraints of different nature, from airspace and airport congestion up to climatic conditions or even crews working conditions. Such a complex problem requires different methods for an efficient solution. In this study by using network optimization method and applying different operational constraints on... 

LOOP accident is one of the most important accidents in NPPS and it leads to loss of power supply of the RCP pumps which are the main pumps of primary circuit. Subsequently trip of the rector occurs. In safety analysis, concerning worst conditions, assumes that after a small period of time, main generator of plant stops working and loss of AC power supply of all power plant loads including safety systems ocures. To control of this accident, it’s necessary to startup and load backup power supply system (EDGs) for at least one safety channels, if not, the accident moves forwards and becomes S.B.O accident which is more important accident that ends to core damage because of stops working of all... 

Towards basic-applied Research in the System Sciences fields, this Research has been to try to understand the behavior patterns and Functional Architecture of parasitic organisms and Use these in Social-Economic Systems. In this research four scenarios for parasite behavior were found and based on one of them, the recent "Financial Crisis in Greece" has been evaluated. The results show that the developed model, can be effective in similar conditions.